Prior to the hybridization process, the microarray slides were blocked by immersion into 5 x SSC (1x SSC is 0.15 M NaCl; 15 mM sodium citrate, pH 7), 0.1% (wt/vol) SDS, 1% (wt/vol) bovine serum albumin for 1 h at 42 C. Then, the slides were washed by two successive immersions in MilliQ water at room temperature, followed by a final wash with isopropanol. The slides were spin-dried by centrifugation at 1,500 x g for 5 min, and used within the next hour. Equal amounts of Cy3- and Cy5-labeled cDNAs, one of them corresponding to the control and the other one to the problem to be analyzed, were mixed, dried in a Speed-Vac and reconstituted in 35 ul of hybridization buffer (5x SSC, 25% [vol/vol] formamide, 0.5% [wt/vol] SDS, 5x Denhardt’s solution, 5% [wt/vol] dextransulfate) preheated to 42C. The labelled probe was denatured at 98C for 3 min, applied onto the microarray slide and covered with a glass lid. The slide was then introduced in a humidified hybridization chamber (AHC ArrayIt Hybridization Cassette; Telechem International, Inc.) and incubated for 18 to 20 h in a water bath at 42C, preserved from light. Following hybridization, the microarrays were washed by gentle agitation in 2x SSC, 0.1% [wt/vol] SDS at 42C for 5 min, followed by a 5-min wash at room temperature in 1x SSC, two 5-min washes in 0.2x SSC, and a final 5-min wash in 0.1x SSC. Finally, the slides were spin-dried in a centrifuge at 1,500 x g for 5 min, and scanned. (Parameters: Chamber type = OTHER: AHC ArrayIt Hybridization Cassette; Telechem International, Inc, Quantity of label target used = 6, Mass unit = Micro gram, time = 20, Tiny time unit = hours, Volume = 35, Volume unit = Micro litre, temperature = 42)